Farm product protecting bag

ABSTRACT

A farm product protecting bag adapted to be placed over a farm product, such as fruit, vegetable or flower, to protect it from diseases or harmful insects, wherein the bag contributes to improvement of quality, such as sugar content, color or external appearance of the farm product, the bag mount efficiency being increased to facilitate quality control. The bag is in the form of a transparent or semitransparent and/or light-transmitting porous film of plastic material with at least part or all of the surface of the bag being air-permeable or gas-permeable and having many fine pores impermeable to water, the bag comprising a bag main body having an opening that opens in one direction, and an attaching section for attaching the bag main body to the support portion of the farm product, it being preferable that the diameter of the largest of the fine pores be in the range of 50-500 μm and that the void area percentage be in the range of 0.7-10%, the fine holes being through-holes or closed holes closed at one end, it being preferable that the surface formed with irregularities in the peripheral edge of the fine holes be directed to at least the inside of the bag.

TECHNICAL FIELD

The present invention relates to a bag for protecting a farm product from harmful insects by placing the bag over the farm product during the cultivation of fruit such as graves and pears, vegetables or flowers, and more particularly to a farm product protecting bag contributing to improvement of quality such as sugar content, color or external appearance of a farm product by not only preventing the farm product from burns due to hot air with an air-permeable or gas-permeable film of plastic material but also increasing bag mounting efficiency to facilitate quality control.

BACKGROUND ART

Heretofore, paper bags have been used for protecting farm products, for example, fruit such as grapes, pears, apples, peaches and any other kinds of fruit during the cultivation of them. However, because water-repellent finishing is added to the paper bag with paraffin or olefin resin coated thereon so that it is not broken by becoming wet with water, the bag loses gas-permeability with the interior thereof losing contact with the air outside, thus causing mold and unwanted bacteria to breed. Not only this problem above but also another problem exists in that the hot air left in the bag during the heat of the day in summer causes burns to be produced in part of the fruit kept in contact with the upper portion of the bag.

During the growth of fruit, moreover, a paper bag of the sort mentioned above lacks transparency, which necessitates time and labor when work of thinning out the fruit is done while the condition of the fruit inside the paper bag is observed as it has to be broken so as to observe the inside of the fruit. Although there is a paper bag, part of which is made of a transparent film, the spread of the paper bag has not yet been attained partly because the paper bag is costly and partly because it is still inconvenient in that the transparent portions are attached such that they are directed to one and the same direction whereby to allow the inside of the bag to be observed from one direction. Still another problem is that the fruit has to be protected from bird damage by covering the upper portion of the paper bag with an umbrella-like plastic film because the conventional paper bag is easily broken when the bird pecks at it, thus allowing the fruit to be eaten away, that is, resulting in doubling trouble.

It has also brought up a further problem that farm products other than the aforementioned fruit; for example, vegetables such as tomatoes, mini-tomatoes, cabbages, Chinese cabbages and asparagus; mushrooms such as enoki mushrooms and hens-of-the-woods; and flowering plants such as roses and phalaenopsises often suffer from damage by harmful such as extremely small harmful insects called thrips that eat pollen, leaves, flowers, fruit and young branches during their growth.

On the other hand, there is a bag body formed as a substitute for the paper bag above, with a transparent or semitransparent plastic film having air vent holes (JP-A-10-52180 (pp 1-4, FIG. 3). However, the present invention is different from what is described in JP-A-10-52180 in that the latter is provided with a shield portion on the opening side of the bag body and water vent holes (called water vent pores in JP-A-10-52180) in the base portion thereof; it is deducible from the latter invention thus laid-opened that the water vent holes are provided in the base portion of the bag in order to discharge the water infiltrated inside since the infiltration of water from the outside is certainly possible when the diameter of the air vent holes exceeds a predetermined range. Nevertheless, the problem is that harmful insects such as ants, cockroaches, thrips and so on may march into the bag body through the water vent holes.

DISCLOSURE OF THE INVENTION

In order to solve the foregoing problems, the present inventor, on persistent study, has arrived at this invention, wherein fine pores provided in a bag main body are air-permeable or gas-permeable and about the size of allowing no water to pass therethrough. Consequently, as long as the opening of the bag main body is sealed up, water never infiltrates into the bag and water drain holes need not be provided, whereupon there is no fear that the bag is invaded by harmful insects through the water drain holes. The inventor reasoned that when the air inside the bag was replaced with the air outside by letting air pass through the fine pores, the replacement of air was closely related to the fine pore density as well the pore opening and the inventor provided the diameter of fine pores and a range of void area percentages or a range of opening rates that create the best environmental conditions for farm products. An object of the invention made to solve the foregoing problems is to provide a farm product protecting bag which is notable for its effect of promoting and protecting farm products in farming without insecticides or cultivation using reduced amount of agricultural chemicals in particular and contributes to improvement of quality and yield of fruit and increasing the bag mounting efficiency.

Means for Solving the Problems

In order to solve the foregoing problems according to the invention, a farm product protecting bag for protecting a farm product by covering the farm product with the bag during the process of cultivating the farm products such as fruit, vegetables and flowers, is characterized in that the bag has an opening which opens in at least one direction; at least part (including a portion on the opening side) or all of the surface of the bag has many fine pores which are air-permeable or gas-permeable and impermeable to water; and the bag is in the form of a transparent or semitransparent and/or light-transmitting porous film of plastic material.

According to the invention, “fine pores which are air-permeable or gas-permeable and impermeable to water” means that “when the farm product protecting bag is used generally in the normal condition, the fine pores are at least permeable to air but impermeable to water” and granted that the bag lets water in under a specific condition other than what is described above, it is not intended for the farm product protecting bag to be excluded from the invention for the reason above.

In order to solve the foregoing problems according to the invention, a farm product protecting bag for protecting a farm product by covering the farm product with the bag during the process of cultivating the farm products such as fruit, vegetables and flowers, is characterized in that the bag has an opening which opens in at least one direction; at least part (including a portion on the opening side) or all of the surface of the bag has many fine pores which are air-permeable or gas-permeable and impermeable to water; and the bag comprises a bag main body in the form of a transparent or semitransparent and/or light-transmitting porous film of plastic material and an attaching section for attaching the bag main body to the support portion (including the support branch portion) of the farm product.

In order to solve the foregoing problems according to the invention, a farm product protecting bag for protecting a farm product by covering the farm product with the bag during the process of cultivating the farm products such as fruit, vegetables and flowers, is characterized in that the bag has an opening which opens in at least one direction; the bag is a multiple bag, each of the bags therein being formed with a film of plastic material; and at least part (including a portion on the opening side) or all of the surface of each bag has many fine pores which are air-permeable or gas-permeable and impermeable to water.

In order to solve the foregoing problems according to the invention, a farm product protecting bag for protecting a farm product by covering the farm product with the bag during the process of cultivating the farm products such as fruit, vegetables and flowers, is characterized in that the bag has an opening which opens in at least one direction; the bag is a multiple bag, each of the bags therein being formed with a film of plastic material; the bag comprises a bag main body wherein at least part (including a portion on the opening side) or all of the surface of each bag has many fine pores which are air-permeable or gas-permeable and impermeable to water; and an attaching section for attaching the bag main body to the support portion (including the support branch portion) of the farm product.

In order to solve the foregoing problems according to the invention, the farm product protecting bag is preferably characterized in that the diameter of the largest of the fine pores is in the range of 50-500 μm and that the void area percentage is in the range of 0.7-10%.

In order to solve the foregoing problems according to the invention, the farm product protecting bag is preferably characterized in that the plastic film is formed such that a protrusion is formed on the peripheral edge of each fine pore on one or both sides of the film and that any one side with the protrusions thus formed is directed to the inner side of the bag main body (claim 6).

In order to solve the foregoing problems according to the invention, the farm product protecting bag is preferably characterized in that the fine pores are through-holes passed from one side toward the other side of the plastic film or closed pores made by punching in the direction of the thickness of the plastic film excluding an extremely thin film portion in the neighborhood of the surface of the other side of the plastic film, with one end closed by the extremely thin film.

In order to solve the foregoing problems according to the invention, the farm product protecting bag is preferably characterized in that the plastic film used to form the farm product protecting bag selectively transmits a ray of light out of rays of the sun, having wavelengths on which coloration, sugar content or growth of farm products is promoted.

In order to solve the foregoing problems according to the invention, the farm product protecting bag is preferably characterized in that the plastic film used to form the farm product protecting bag is at least a kind of functional film selected from the group consisting of a raw decomposable film, an ultraviolet ray absorbing film, an antibacterial or germicide film, a minus ion generating film, a far-infrared ray generating film and a deodorizing or aromatic film.

In order to solve the foregoing problems according to the invention, the farm product protecting bag is preferably characterized in that the attaching section is formed from part of the bag main body or what is formed separately from the bag main body and then secured to the bag main body.

Operation

The farm product protecting bag according to the invention is formed of the plastic film having the fine pores as described above and the bag is not broken by the pecking of birds and is capable of completely blocking the penetration of harmful insects such as ants, cockroaches, slugs, shield bugs and thrips. Further, since the bag is impermeable to water and prevents the infiltration of rainwater and a liquified agricultural chemical into the bag, no water vent holes are needed to be provided and consequently there is no fear that the bag is invaded by harmful insects through the water vent holes. Even if rainwater infiltrates into the bag in a gale because of a typhoon, the rainwater within the bag is vaporized as the fine pores are permeable to air and evaporated through the fine pores. Moreover, as the air inside the bag is freely replaceable with the air outside, the hot air in the bag is removed in the daytime whereby to uniformize the temperature distribution inside, so that the fruit is prevented from burns, whereas the chill outside the bag at night is introduced so as to make the condition inside close to a natural atmosphere. Thus, difference in temperature between daytime and nighttime grows to increase the sugar content as well as the quality of the fruit. Further, the light-transmitting bag main body allows sunlight to be taken in natural conditions, which results in increasing the coloration degree of farm products and providing external appearance excellent in colorability similarly as if they are cultivated in the sunlight.

The reason for the use of a multiple bag, particularly a double bag for protecting farm products is that the inner bag is composed of a transparent or semitransparent and/or light-transmitting film for transmitting sunlight or selectively transmitting only sunlight having a specific wavelength and that the outer bag out of the double bag is composed of a film for shielding sunlight or part of the sunlight. In the case of a bag for protecting an apple, for example, the double bag is placed over the fruit at the initial stage of growth of the fruit so as to shut off sunlight and only the outer bag is removed at such a stage that the fruit has grown to a certain level, whereby the fruit is colored red because it is irradiated with sunlight transmitted through the transparent inner bag. Moreover, it is preferred to add transparent organic red pigments to the inner bag in order to facilitate the transmission of rays with red wavelengths so that the red coloring matter of the fruit is enlarged. Otherwise, the double bag is placed over the farm product during the growing period of the farm product and the outer bag is removed after the harvest of the farm product; the inner bag may be used as a goods wrapping bag. The multiple bag is not limited to the double bag but may be what has three or more of sheets, if necessary.

The diameter of the largest of the fine pores of the farm product protecting bag according to the invention can be set to range from 50 to 500 μm, so that the penetration of extremely small harmful insects like thrips is blocked by the air-permeability, gas-permeability and impermeability to water. In order to secure a sufficient quantity of air-permeability in consideration of a case where the quantity thereof is insufficient because the pore diameter is made smaller than necessary only by determining the maximum value of the diameter of the fine pores and the minimum value of the void area percentage, the range of the diameter of the largest of the fine pores is determined as described above, with the void area percentage being determined in the range of 0.7-10%. The void area percentage in this case means the numeral value given by the percentage of the total void area to a unit area.

Further, with respect to the farm product protecting bag according to the invention, the protrusion is formed on the peripheral edge of each fine pore on one side or both sides of the film and as any side on which the protrusions are formed can be set to face the inside of the bag main body, the protrusions make a point-contact to the surface of the fruit (FIG. 5). In the case of a conventional simple porous film without protrusions, because the film is brought into intimate contact with the surface of the fruit without any space, the passage of air is impeded and this has caused burns due to hot air. Although a shield portion has been provided for preventing burns by heat, this arrangement has a drawback in that the colorability and the sugar content are lowered by shielding sunlight. In the case of the invention, an air current passes from the fine pores via the gap between the protrusions and the contact portions to radiate the hot air outside whereby to prevent the burns by heat, which functions as what increase the colorability and the sugar content as it is unnecessary to provide the shield portion. Moreover, the protrusions of the opposed films, or the protrusions and the plane of the inner side of the bag main body make contact with other whereby to prevent the films from sticking to each other in comparison with a case where the planes of the films make contact each other; as the bags are readily open, the bag mounting efficiency is improved.

Since the protrusion is formed on the peripheral edge of each fine pore on the one side or both sides of the film, the bag formed by directing the film surface having the protrusions to the inside of the bag main body restrains the so-called water conveyance force derived from the capillary phenomenon caused by drops of rainwater introduced into the bag through the fine pores, the rainwater being passed through the gap in the contact portion between the protrusions on the film surface and the fruit, and improves the impermeable-to-water performance of the film. As the air current from the fine pores is simultaneously increased, the function of emitting the hot air outside is improved further.

The farm product protecting bag according to the invention can be a porous film having closed pores and air can be transmitted via the extremely thin film portion with one ends of fine pores being closed, so that the penetration of bacteria, to say nothing of harmful insects, may be blocked.

Additives such as a coloring material selectively transmitting wavelengths of sunlight for promoting the coloration of fruit and an ultraviolet ray absorber can be added to the farm product protecting bag according to the invention. The fruit can be colored deep and sugar content may be increased by adding to the bag a transparent organic coloring material for proliferating the coloring matter of the black-purple color of the grape.

The farm product protecting bag according to the invention is capable of promoting the growth of farm products and raising the value of them by using various functional films as described above.

The farm product protecting bag according to the invention is equipped with the attaching section for attaching the bag to the support portion of an adherend. As the attaching section is formed from part of the bag main body or formed separately from the bag main body and then secured to the bag main body, bag mounting work is facilitated. Since the attaching section is thus secured to the bag or formed as part of the bag, time and labor required to take out the attaching sections one by one can be dispensed with, whereby the bag mounting work is easily done and the bag is securely mounted to the support portion. Specific examples of the attaching sections will be described later.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a farm product protecting bag using an adhesive for an attaching section according to an embodiment of the invention.

FIG. 2 is a perspective view showing a condition in which the farm product protecting bag using the adhesive for the attaching section according to the embodiment of the invention is employed.

FIG. 3 is a perspective view illustrating the farm product protecting bag using wire for the attaching section according to the embodiment of the invention.

FIG. 4 is a perspective view showing a condition in which the farm product protecting bag using the wire for the attaching section according to the embodiment of the invention is employed.

FIG. 5 is an illustration showing a contact surface condition between fruit and the farm product protecting bag according to the embodiment of the invention.

FIG. 6 is a perspective view illustrating a farm product protecting bag using wire for an attaching section according to another embodiment of the invention.

FIG. 7 is a plan view illustrating a farm product protecting bag according to still another embodiment of the invention, wherein both end portions of a belt-like attaching section are welded to the respective sides of a bag main body.

FIG. 8 is a perspective view illustrating a farm product protecting bag according to a further embodiment of the invention, wherein a belt-like attaching section is formed by making a cut into part of the bag main body.

FIG. 9 is a plan view illustrating a condition in which an attaching section formed with a small piece is welded to a bag main body in the neighborhood of the opening of the bag main body.

BEST MODE FOR CARRYING OUT THE INVENTION

A representative embodiment of the invention will now be described by reference to the drawings. However, the invention as claimed in the application concerned is not limited by the following embodiment thereof.

An embodiment of the invention.

In the embodiment of the invention shown in FIGS. 1 to 4, reference numeral 1 denotes a farm product protecting bag; 11, a bag main body; 12, an attaching section; 13, fine pores; and 14, a notch. The bag main body 11 is in the form of a transparent or semitransparent porous film of plastic material with substantially all of the surface of the bag being air-permeable or gas-permeable and having many fine pores 13 impermeable to water.

Although the fine pores are provided in part of the side of an opening 15 as shown in FIG. 1, the fine pores 13 may be provided in the whole surface of the bag. A range of providing the fine pores can be decided properly in consideration of the temperature in the bag. As the hot air in the bag tends to ascend and in order to efficiently discharge the hot air outside, the fine pores 13 are preferably provided in the neighborhood of the opening 15 at least when the bag is mounted in a turned-up condition so that air is readily escapable upward. Otherwise, the fine pores 13 are preferably arranged so as to increase air vent efficiency by increasing the diameter of fine pores, the pore density or the void area percentage. In other words, the bag may be provided in a prescribed arrangement depending on the direction in which the bag is mounted, for example, in the neighborhood of the opening of the bag, the base portion of the bag or the middle portion of the bag by properly varying the diameter of fine pores 13, the pore density or the void area percentage according to the region of the bag where the fine pores 13 are arranged.

The material of the plastic film is not limited to a specific one. However, the material may be selected from among the following: a polypropylene (PP) film, a biaxial oriented polypropylene film (OPP), a polystyrene (PE) film, a general-purpose polystyrene (GP-PS) film, a high-impact polystyrene (HI-PS) film, a biaxial oriented polystyrene (OPS) film, a polyester (PET) film, a polycarbonate (PC) film, a polyvinyl alcohol (PVA) film, a polyvinyl chloride (PVC) film, an ionomer film, a cellulose plastic film, a thermoplastic elastomer film and so on depending on the purpose. In addition to the single films above, use may be made of a co-extrusion film or a multilayer film using dry lamination or sand lamination via an adhesive resin layer.

Further, a film for the purpose is such that it is made of, for example, starch or dextrin decomposed by microbes. In addition, various functions stated above can be attained by adding or applying to a bag, or filling up the bag with, at least what is selected from the group consisting of an ultraviolet ray absorber for absorbing a specific ultraviolet ray; an antibacterial agent or a germicide made of silver or copper metal powder, for example; ceramic powder generating minus ions or far-infrared rays; granite powder or carbon powder (e.g., charcoal powder); and

-   -   a deodorizer or an aromatic.

The gas-permeability is secured on condition that the diameter of the largest of the fine pores is 50 μm, preferably 70 μm or greater and when the diameter thereof exceeds 500 μm, water-permeability may occur. Therefore, a range of diameters of fine pores should be 50-500 μm, preferably 70-400 μm and most preferably 90-200 μm. In this embodiment of the invention, tests were carried out by using three kinds of porous transparent OPP films 25 μm thick as listed in Table 1. TABLE 1 Embodiment 1: Embodiment 2: Embodiment 3: Pore configuration: circle circle circle Number of pores 1,786,000 890,000 620,000 (/m²): Mean pore diameter: 100 200-300 350-450 Void area percentage 1.4 4.4 7.8 (%): A method of producing the porous films comprises, for example, sandwiching polyolefin films between a driving roll having planted needles heated to a film melting point (of about 200° C.) or higher or an emboss roll having bosses and a backup roll (a predetermined gap being set therebetween) and fusion-punching a number of fine pores at a synchronous line speed. At this time of fusion-punching the pores, a relatively high protruded portion due to the molten resin stock is formed on the peripheral edge of the pore on one side of the film, whereas a relatively low protruded portion is formed on the other side of the film. According to this embodiment of the invention, two sheets of the films are put on top of each other so that the sides of the films having the relatively high protruded portions face each other and then the periphery of the combined films, excluding the opening, is fused for cutting so as to form a bag.

In the case of the multiple bag above, the number of films may be doubled to form a bag; for example, a double bag for an apple is formable by putting transparent porous films on top of each other, then adding one sheet of shield porous film to both sides of the double bag and fusion-cutting the periphery of the bag formed with four sheets of films in total as in the preceding case. The porous film above includes a layered film that is formed with a plurality of single porous films stacked up with fine pores punched by passing heated needles therethrough whereby to combine the plurality of films together with a dot pattern. In the case of the latter layered film, each single film can readily be separated by peeling it off by hand.

In addition to using the heated needles for punching fine pores, there are various methods of punching fine pores, including a method of blowing off powdered ore at high speed from one side through the other side of the plastic film; a method of using a laser beam; a method comprising the steps of placing a film continuously along the surface of a cylindrical roll having a number of through-holes first, heating and sucking the film from the inside and cutting the film portion sucked along the inner side of the cylindrical roll; a method of jetting out heated gas and the like from the inside of the through-holes provided in the cylindrical roll above; and a method comprising the steps of placing a film continuously along the surface of a cylindrical roll having a number of pits first, heating the surface of the film with a gas burner and causing the film kept in contact with the pits to shrink on receiving the internal stress. The porous films according to the invention include those produced under all sorts of punching methods and are not restricted by any punching or bag-making method.

A film with one end closed by an extremely thin film portion is producible substantially like what is described in an application for patent No. 2002-220722 made by the present applicant. For example, a laminated film prepared by laminating an outer polystyrene layer relatively great in gas-permeability, a polyethylene layer and a heat-sealing polyester layer in sequence, using dry or PE sand lamination via an adhesive resin layer (the thickness of these layers ranging from 50 to 25 and to 25 μm in order) is used. Then, the film is sandwiched between a driving roll having heated needles planted in the surface and a backup roll (a predetermined gap being set therebetween) with the inside of the film (polyester layer) directed to the heated needles whereby to fusion-punch innumerable fine pores at a synchronous line speed with an extremely thin film portion of about 5 μm left in the neighborhood of the outer side (polystyrene layer) of the film.

Although the temperature of needles to be heated is set at the melting point (about 200° C.) or higher, it is preferably so controlled as to be set at a suitable temperature in consideration of the line speed. As the so-called roll with heated needles above is arranged so that the needles are planted substantially over the whole surface of the roll that the film contacts and heated, use can be made of a squeezing roll with bosses formed on the surface of the roll. It is thus possible to obtain a transparent gas-permeable film closed by an extremely thin film portion of about 5 μm in the neighborhood of the surface of the outer film, with innumerable fine pores about 0.4 in diameter and punched at intervals of about 0.7 mm. The thickness of the extremely thin film portion is determined in relation to the roll-to-roll gap, the film processing speed, the melting point or processing temperature of the film; actually, it is controlled by changing the film processing speed.

As shown in FIG. 1, the attaching section 12 in the neighborhood of the opening of the bag main body 11 is such that one side of the opening 15 sticks out longer than the other and a notch 14 is provided vertically at the substantially center of a stickout portion 16 and directed to the neighborhood of the opening, an adhesive layer 17 and a parting layer 18 being formed in this order on the inner side of the stickout portion 16. When the bag main body 11 is mounted to the support branch of fruit, the opening of the bag main body 11 is opened to take in the fruit inside and the fruit is covered with the bag main body 11. Then, the parting layer 18 is peeled off and the right and left of the stickout portion 16 are folded such that the right and left thereof intersect around the center of the support branch. Further, the adhesive layer 17 is stuck on the opposite film side so as to seal the opening. The adhesive layer 17 and the parting layer 18 may be provided on the opposite side of the folded stickout portion 16.

FIG. 3 illustrates a case where wire 19 as the attaching section is mounted to the neighborhood of the opening of the bag main body 11. The notch 14 may be provided as the need arises. As shown in FIG. 4, the wire 19 can be fastened by winding it on the support branch. The wire 19 should preferably be covered with plastics or sandwiched between two sheets of belt-like plastics. FIG. 6 illustrates a case where the whole wire 19 is vertically thermowelded to one side of the bag main body with a belt-like cut formed along the wire 19. Moreover, a hot-press portion may be formed in the lower end portion of the notch as the need arises. Further, the wire 19 may be provided on the whole peripheral edge or along part of the peripheral edge of the opening 15 of the bag main body 11 (not shown).

As shown in FIG. 7, a belt-like attaching section is formed separately from the bag main body and horizontally disposed in the neighborhood of the opening of the bag main body 11 and both ends of the attaching section are thermowelded to the respective sides of the bag main body 11; only one end of the belt-like attaching section 12 may be welded thereto. The material of the belt-like attaching section 12 is not limited to a specific one but may be what can be thermowelded to the bag main body 11 and may preferably be a non-elongation film in at least the longer direction of the belt-like attaching section. The periphery of the bag main body 11 excluding its opening is sealed by stacking two sheets of porous plastic films and a belt-like plastic film in this order in a suitable position and subjecting the bag main body 11 to the fusion cutting, so that the farm product protecting bag 1 with both ends or one end of the attaching section 12 welded to the bag main body 11 can be formed at one process step.

When the bag is mounted to the support branch of the farm product, one end of the belt-like attaching section 12 is removed from the bag main body 11 and wound around the opening 15 of the bag main body 11 several times and for what has only one side welded to the attaching section 12, only the one side thereof is wound around the opening 15 of the bag main body 11 several times so as to tighten the opening 15 by inserting the end above into the gap and drawing out the end, whereby the bag main body 11 can be mounted to the support branch with the opening 15 sealed up. For the fusion cutting, other than pressurizing the plastic film with a heated fusion-cutting blade, a high-frequency welder may be used in the case of a vinyl chloride plastic film and an ultrasonic welder may be used in the case of an olefin plastic film.

As shown by way of example in FIG. 8, the attaching section 14 is such that the notch 14 and a belt-like string 12 are formed with a hot-pressed portion 24 on the upper end portion of one side of the bag main body 11 itself. Although the notch 14 may be formed by using scissors or a cutter, it can be processed at one step by fusion-cutting the upper end portion of the hot-pressed portion 24 with a flat blade and the notch with the fusion-cutting blade. Like the example shown above, the high-frequency welder or the ultrasonic welder may be employed, depending on the material for use. Moreover, the watertightness of the opening 15 in a closed condition may be improved by sticking cloth such as a belt-like fabric to the inner peripheral portion of the opening 15 (not shown).

FIG. 9 illustrates a condition in which the attaching section 12 as another example having a hole 25 for sandwiching the bag main body formed in the central portion of a small piece in the form of a flexible hard thin plastic plate, and the notch 14 continuous to the hole 25 therefor is welded to the neighborhood of the opening 15. When the opening 15 of the bag main body 11 is narrowed before being forced into the hole 25 for sandwiching the bag main body through the notch 14, the bag main body 11 can be mounted to the support portion with the opening closed.

EMBODIMENTS OF THE INVENTION

30 to 500 sheets of farm product protecting bags using the three kinds of porous films obtained according to the above embodiments of the invention, and conventional paper bags subjected to water-repellent finishing as comparative examples, each having a water vent hole in the base portion thereof, were prepared and placed over purple-black grapes (called Kyohou) on the same condition before being tested, the results of which are shown below. The tests were carried in vineyards in Yamanashi and Shiga Prefectures. The bags were prepared from May to June in 2002 in order to start the tests late in June to mid-July. While the observation of the inside of each bag was continued, the grapes were harvested early to late in September and 20 examiners were engaged in evaluating the sugar content, the external appearance and so forth. Table 2 shows the test results. TABLE 2 Embodiment 1: Embodiment 2: Embodiment 3: Sugar content: very sweet very sweet very sweet Coloration deep deep deep degree: black-purple black-purple black-purple Occurrence of nil nil nil burns: Degree of damage nil nil nil from harmful insects: Visual inspection high high high efficiency: Comparative example: Sugar content: little sweet Coloration red-purple degree: Occurrence of present in burns: upper portion Degree of damage slightly high from harmful insects: Visual inspection visual inspection efficiency: is difficult

As shown in Table 2, the farm product protecting bags according to the embodiments of the invention exhibited excellent results in any terms of the sugar content, coloration degree, burns and damage from harmful insects, whereas in the case of the conventional paper bag, the sugar content and the coloration degree were found inferior to the invention. No occurrence of burns by heat in the grapes and the absence of discoloration of the bags according to the embodiments of the invention make it feasible to directly use them as goods wrapping bags. On the contrary, not only a noticeable occurrence of burns by heat in part of the grape kept in contact with the upper interior of the bag, but also a change of color to red-brick due to the growth of mold inside the bag as the comparative example makes it quite impossible to use the conventional bags as goods wrapping bags. Further, there was no difference between the nutrition transfer percentages from the trunk in both the embodiments of the invention and the comparative examples. With respect to the coloration of the fruit, it was confirmed that the greater the irradiation of light, the deeper the fruit color became; and the deeper the fruit color, the greater the sugar content became with white powder formed on the surface.

When the inside of every bag as the comparative example is visually examined, the whole bag has to be broken to see the condition of the fruit inside. Then, the bags have to be hung on the branches again and this work is extremely troublesome, whereupon the condition of the fruit is made quite obvious from the outside according to the embodiments of the invention and as it is only needed to select those to be thinned out, greater efficiency in the thinning-out work is achieved while waste in time is avoided. Even though the bag is provided with a window in the form of a transparent film, the work efficiency is not increased so much because the whole inside of such a bag is hard to observe from the outside. Moreover, no damage from birds was seen as far as the embodiments of the invention are concerned. On the contrary, a great deal of traces that birds pecked at from above the bags were found in the case of the comparative examples. Based on the results obtained above, it has been confirmed that the invention is satisfactorily applicable to any other farm products such as fruit, vegetables and flowers.

EFFECT OF THE INVENTION

As the farm product protecting bag according to the invention is arranged as set forth above, the penetration of the harmful insects into the bag is completely blocked and the bird damage caused by the pecking of birds is prevented. Further, the farm products are prevented from burns by heat by replacing the air inside the bag with the air outside, and mold and unwanted bacteria are prevented from breeding whereby to improve quality and reduce the number of inferior goods. Consequently, since no shield portion is needed to be provide so as to prevent the farm products from burns, the degree of irradiation of sunlight is raised and sugar content as well as colorability is improved. The bag mounting work is simple and as the harvesting time is made selectable by observing the growing condition of the farm products from the outside with the bag mounted. The farm products thus harvested can be shipped directly without replacing the bags with wrapping bags. Moreover, as the thinning-out work can be conducted by choosing those needed on observing the farm products from the outside, not only work efficiency is improved but also useless time and labor to be expended by breaking the bags for confirming purposes are saved. Therefore, an excellent effect is achievable in multiplicity of use as loss in time and cost is reducible with the processing of bags being performable relatively simply and economically. 

1-10. (canceled)
 11. A farm product protecting bag for protecting a farm product such as fruit, vegetables and flowers by covering the farm product with the bag during the process of cultivating the farm product, the bag having an opening which opens in at least one direction, at least part, including a portion adjacent the opening, of the bag having many fine pores which are air-permeable or gas-permeable and are impermeable to water, the bag being comprised of a transparent or semitransparent and/or light-transmitting film of plastic material having the fine pores, and a protrusion being formed on the peripheral edge of each of said fine pores on one face or both faces of the film, a face on which the protrusions are formed facing inside of the bag.
 12. A multi-layered farm product protecting bag for protecting a farm product such as fruit, vegetables and flowers by covering the farm product with the multi-layered bag during the process of cultivating the farm product, the multi-layered bag having an opening which opens in at least on direction, the multi-layered bag being comprised of a plurality of nested bags, each of the nested bags being comprised of a film of plastic material, at least part, including a portion adjacent the opening, of each of the nested bags having many fine pores which are air-permeable or gas-permeable and are impermeable to water, and a protrusion being formed on the peripheral edge of each of said fine pores on one face or both faces of the film, a face on which the protrusions are formed facing inside of the multi-layered bag.
 13. A farm product protecting bag as claimed in either claim 11 or claim 12, wherein the fine pores comprise largest pores having diameters in a range of 50-500 μm and wherein the void area percentage is in the range of 0.7-10%.
 14. A farm product protecting bag as claimed in either claim 11 or claim 12, wherein the fine pores are through-holes passing from one face to the other face of the plastic film.
 15. A farm product protecting bag as claimed in either claim 11 or claim 12, wherein the plastic film includes a coloring material.
 16. A farm product protecting bag as claimed in either claim 11 or claim 12, wherein the plastic film is selected from the group consisting of a raw decomposable film, an ultraviolet ray absorbing film, an antibacterial or germicide film, a minus ion generating film, a far-infrared ray generating film and a deodorizing or aromatic film.
 17. A farm product protecting bag as claimed in either claim 11 or claim 12, further comprising an attaching section for attaching the bag to a support portion, including a support branch portion, of the farm product, wherein the attaching section is formed from part of the bag or has been formed separately from the bag and then secured by thermowelding to the bag.
 18. A farm product protecting bag as claimed in either claim 11 or claim 12, further comprising an attaching section for attaching the bag to a support portion, including a support branch portion, of the farm product, wherein the attaching section is a belt-like strip of a film which is substantially non-elongating iii a lengthwise direction thereof.
 19. A farm product protecting bag as claimed in either claim 11 or claim 12, wherein the fine pores are closed pores formed by punching in the direction of thickness of the plastic film from one face to the other face of the plastic film, with one end of each of the pores being closed by an extremely thin film portion in the neighborhood of said other face. 